It feels like the author is only planning this story one chapter at a time, with no longer plans whatsoever. Pretty much everything happening seems random, including the dialogue. Moreover, Hana is the only character with a defined personality (denpa, electromagnetic girl). The devil and the hero are basically identical, the followers are gray one-trait characters if even that. Now out of the blue we get another weirdo, who makes no sense because the story hadn't make any preparations.
This shoujo series is basically the equivalent of ecchi shounen series. Both can work with no plot to speak of, as long as there are pretty bishounen/bishoujo.